Armature-actuating mechanism for magnetos



P. BROWQQ ARMATURE ACTUATING MECHANISM FOR MAGNETOS Filed Jan. 28. 1926INVEN'TOR.

ATTORNEYS.

Patented Feb. 7, 1928.

UNITED STATES PATENT OFFICE.

PHELPS BROWN, F SPRINGFIELD, MASSACHUSETTS.

ARMATURE-ACTUATING MECHANISM FOR MAGNETOS.

Application filed January 28, 1926.

, the armature 1S moved into and out of contact with magnetic poles andis initially moved out of contact with its poles by an inelastictransmission of force followed, if and when desired, by the expansiveeffort of a previously stressed elastic armature driving means. Examplesof magnetos of this type will be found in the following U. S. LettersPatent :Brown and Clark No. 1,389,382, April 7, 192%; I-lendrickson llo.1,l90,17l, April 15, 1924; Brown and liendrickson No. 1,517,948,December 2, 192d; Louis No. 1,517,997, December 2, 192-1; and Brown etal., No. 1,532,799, April 7, 1925.

In each of these patents, the armature drive spring is placed under itsdriving tress by the reciprocable member, which runctions to start thearmature away from its poles by an inelastic transmission of force,during its active and armature starting stroke. Also the drive springmoves with the reciprocable member and thereby partakes of its kineticenergy, wherefore such energy is applied to the armature in addition tothe energy due to the expansion of the spring. While this arrangementwork satisfactorily, it is found that on high engine speeds the armatureis moved more violently and through reater distances than is necertending to result in more rapid wear and tear on the parts and somewhatnoisier operation than is desired.

my prior U. S. Letters Patent No. i,d88,975, April 1, 192 1, I disclosea magneto, erein the drive spring is made up during the return stroke ofthe armature and is moved toward its poles between quite heavy balancedsprings, which cause the armature to be seated with relatively littlenoise on its poles. Also, the drive spring acts solely by its expansiveeffort and is not itself moved by the 'cciprocable member of theactuating mechanism. This arrangement, due to the heavy balancedsprings, requires a considerable amount of force to operate it. l hepresent invention seeks to provide an improved armature actuatingmechanism involving the features of both of the two prior arrangementsdescribed with a miniin ug of the disadvantages forth.

are particularly, it is an object of the Serial No. 84,509.

invention to provide in an armature actuating mechanism, which functionsto break the magnetic hold on the armature by an inelastic transmissionof force thereto, a drive spring which acts between a stationaryabutment and the armature so tnat the spring does not, as heretofore,acquire kinetic en ergy from other moving parts of the mechanism.

It is also an object of the invention to pro vide, in a mechanism of theclass described, an arrangement whereby the drive spring is placed understress during the return flight of the armature.

It is a further object of the invention to provide, in connection with amechanism of the type set forth, an arrangement for stressing the drivespring by a force trans mitted through the armature return spring,whereby the armature may be moved toward its poles between springs whichconstantly seek a balance, for the purpose of seating the armature onits poles as quietly as possible.

Another object of the invention is to provide in connection with a sparktiming device for the armature actuating mechanism, means whereby whenthe spark is retarded the tension of the drive spring is automaticallyincreased for the purpose of supplying extra driving force for thearmature at starting or low engine speeds.

Other objects and advantages will appear in the following descriptionand in the illustrative embodiment of the invention in the accompanyingdrawings, in which:

Fig. 1 is a front elevational view of an armature actuating mechanismembodying the invention, showing the parts as positioned at the end ofthe return stroke of the mechanism F ig. 2 is a similar view showing thepositions occupied by the parts during the forward stroke of themechanism when the armature is about to be dislodged from its poles;

Fig. 3 is a view similar to Fig. 2 and shows the parts in the samerelation except that the spark control lever has been moved to retardposition:

Fig. at is a sectional plan View taken on the line H of Fig. 2;

Fig. 5 is a fragmentary sectional elevational view taken on the line 5-5of Fi a; and

Fig. 6 is a fragmentary cross sectional view taken on the line G6 oiFig. i.

Referring to these drawings; a magneto of any suitable construction isindicated at.

, vided on each core 0. I The coils 'w are connected, as in series, toform a generating winding'in whicha spark ISPf-OClllCGd by the describedvariation in reluctance of the magnetic circuit to supply a spark plug,such as s. The coils w are'connectecl, as-in series, to form a chokewinding which, as ina spark control lever 20. The members 18 and 19 arerotatably mounted in a hub 21 which, as shown, is an integral part of aframe ,7 by which the magneto M may be supported from an engine. Thelever 20' has a projection 22, adapted. to engage in any one of aplurality of recesses 23 formed in the rear face of a segmental part 24,which depends from hub 21. The latter is recessed to receive a spring 25which acts on the member 18 with a tendency to move it to the left, asviewed'in 6, for the purpose of releasably holding the projection 22 inany one of the recesses with which I v gaged.

The lever 20 is the means torcontrolling the timing of the spark. It maybe moved from an advanced position, such asthat.

shown inl ig. 2, to a retarded position, such 7 as that shown in F 1g.3, and to various other dica ted, is part of an electrical circuitadaptel to be closed or opened by two relatively movable breaker points6 and b. "The latter is mounted on a stem 00 having a head h which isadapted to be engaged by a lug Z onarmature a during the flight of thelatter away itrom poles 12. whereby points 7) and b are separated. Aspring 7/ tends to hold the points I) and b in contact.

The magneto shown is fully disclosed in United States Letters Patent No.1,557,97 6, granted October 20, 1925, on an invention of Phelps Brownand Terrence G. Louis and reference is made to this patent for a fulldisclosure of the magneto proper. The particular magneto disclosed ismerely illustrative' of a general type with which the invention may beused and the details of the magneto are therefore not important to thepresent invention, which relates entirely to 'mechamsm for moving thearmature a with relation to poles p. v The armature a has fixed theretoa de pending fork 10, provided with spaced arms positions intermediatethese extremes.

lVhen turned from the position shown in mg. 3 to that shown in Fig. 2,the center of'i'he crank pin 17 is moved to the left which affects ashifting of the armature lever to the left in substantially a.horizontal path. The depending arm 16 of this lever, being mored to theleft, is brought closer to the tripping? member, as will be apparentfrom a comparison of Figs. 2 and o so'that the-lever is engaged andmoved, and thus the armatnreyis operated. at an earlier time. v

The arm 16 m". t e armature operating lever 'is providec wi th anintegral web 25 which extends tronithe rear edge ofth-e arm in a.direction opposite to but parallel and below arm 12. This web terminateswith a rearward andright angularlvturn-ed part forming 51 S at to thedriv-esprin 28 11, between which an arm 12 of an armature operating bellcrank lever is received. The outerendof arm 12 is recessed to form aslideway 13 to receive a square block 14., The latter is mounted to turnon a stud. 15,

. screw being held which aasses throu h it and the s aced'arms 11,forming a pivotal connection between the armature and its operatinglever. The

latter has a depending arm 16, which is subjected to the action ofdriving and return springs and a trippmg member, as Wlll appear.

' The'armature operating lever is p votally mounted on a pin 17 which isin fact, a

and having alprojection 29 to extend partv way into this coil spring andhold the same from vertical as well aslateral displacement. The drivespring-28 .is held between the seat or abutment 27 and. a similarsea-tor abutment 30, which is fixed to a screw 31.

The latter is threaded into an ear 32 and thus the position of seat 30with relation toear 32 may be varied as oesired-the in its variouspositions of adjustment" by a lock nut 33. The ear 32'is connected by anintegral and angular shaped web 34'to the spark control lever 20,'abovedescribed. V '7 Thus, when this leveris moved to vary the timing of thesparlrf it also effects a variation in the tension of the drive springby moving the abutment 32 closer to or tar ther away from the abutment27.

the engine started or is running at relatively low speedsthe' drivespring tension it may be env Also, as' th-espark is retarded, as itshould be when from a comparison of Figs. 2 and 3. When the engine isrunning at higher speeds, the spark is naturally advanced and lesstension is needed in the drive spring. Indeed, the drive spring, in sofar as its armature driving function is concerned, can be renderedentirely inactive and the armature may be driven away from its poles atspeeds proportional to engine speed and by an inelastic transmissiontherefrom. This result can be effected inasmuch as the tension of thedrive spring is variable independently of the lever 20 by the screw 32.

The arm 16 of the armature operating lever is provided with roundedabutments 3G and 37 on opposite sides thereof,these'abutments in shapebeing portions of a sphere. A conical hole 88. with the small endopeningcentrally through abutment 36, is also provided in arm 16. A pushrod is adjustably fixed, as by the screw thread connection shown, to aneccentric strap 10 and is ield in its adjusted position by a lock nutThe strap 40 encompasses an eccentric 42, fixed on some suitable shaftlB of the engine, with which the magneto is used,say for example, thecam shaft. The push rod 39 therefore reciprocates continuously and itsforward end s4 is reduced in diameter so as to freely slide in hole 38,by which it is supported. The intersections of the part l with the bodyof the push rod 39 affords a. shoulder d5 which is the armature trippingmember. That is, during the forward stroke of push rod 89 (to the right)the shoulder 45will engage abutment 36, as in dicated in Fig. 2. and oncontinued movementbeyond this position will move arm 16 and cause thearmature to be removed by an inelastic transmission of force from thedrive shaft The movement of the armature in its flight away from thepoles may be effected entirely by the inelastic transmission from pushrod 39 or such transmission may be used merely in the initial stage ofsaid flight for the purpose of breaking the magnetic hold between thearmature and poles so that the drive spring 28 is enabled tosubsequently move the armature. W ll-ether the first or the second planof operation is used depends on the tension of the drive spring As abovedescribed, this tension is variable in two ways. That is, by retardingthe spark, the tension of the drive spring is autoinatically increasedand by adjusting abutment 30 the tension may be varied independently ofthc first adjustment. Accordingly. the combination of inelastic ant.elastic driving forces may be used only in starting the engine or at lowengine speeds when the spark is naturally retarded. Then, when the sparkis subsequently advanced the tension of the drive spring may be loweredto sucn an extent that its expansive effort will not be capable ofmoving the arm 16 as fast asthe push rod 39, wherefore the armature maybe driven entirely by the inelastic transmission described. On the otherhand, the tension of the drive spring may be adjusted so that whateverthe position of lever 20, the expansive effort of the spring 28 willdrive the lever 16 ahead of shoulder to after the latter has ini iallymoved the armature sufliciently to lower the magnetic pull on thearmature enough to enable the spring to act. Wi'h high engine speeds,the inelastic transmission will sutlice with provisions for the elastictransmission only at starting and low engine speeds. With engines whichrun at lower speeds, the elastic transmission may be desired at alltimes although naturally the force exerted by the drive spring need notbe so great at normal running speeds as at starting, wherefore thetension of spring 28 is automatically decreased by the act of ad 'ancingthe spark. The driving mechanism is therefore flexible in the sense thatit may be adjusted over a wide range to suit the various conditionsencountered.

The armature return spring is shown at as a coil spring encompassing theouter part 4% of push rod 39. It is arranged between the abutment 37 andan adjustable abutment in the form of a nut d7, which is threaded on theend of part 44. A washer 48 is preferably interposed between abutment3'? and one end of spring 46' and a similar washer is interposed betweenthe other end of spring d6 and nut 47.

Tl e return spring is placed under stress 1 I 1.1 during LilQ returnstroke of pusn rod 39 and through it the force is transmitted to arm 16and thus to the drive spring 28, which is also made up or placed understress during the return stroke of the armature. The return spring isfirst compressed during the initial stage of the return stroke until itstension becomes equal to that of drive spring 28, after which the arm 16begins to move and during its movement it is held between two springswhich necessarily seek a balance. Consequently, the armature a is movedtoward poles p in a manner calculated to secure a relatively quietseating of it on the poles. The drive spring opposes the magnetic pullon armature a and opposes it to a progressively increasing degree as thearmature nears its poles. The armature therefore moves much moregradually toward its poles than it would if moved directly by the pushrod without the interposition of the elastic connection afforded by thedrive spring. After the armature a has been seated on its poles, thereturn spring continues to compress to take care of the overtravel ofthe eccentric 42 and insure that the armature is held tightly to polesp.

The armature drive spring is thereby conditions.

' will be'incapable of moving mission of force to complete the flight.-

placed under a predetermined amount of tension which, however, may bevaried with in'wide limits as desired to suit different conditions. Thedrive spring tension is, however, insutlicient in itself to overcome theforce of magnetic attraction when the armature is in contact with itspoles. Consequently, some other force is necessary to pry the armatureoff its poles and this effected by the engagementof trip shoulder 45with abutment 36, which results in an inelastic transmission of forcefrom the drive shaft 43 to thearmature for this purpose. Once thearmature has been started from its poles, the dr've spring, ifsufiici-ently tensioned, comes into play and moves the armature rapidlyaway from its poles carrying the arm 16 ahead of shoulder 45 under theseAs above set forth, with high enough engine speed, the movement of thearmature in its downward {light may be effected entirely by theinelastic transmission from push rod 39 and the tension of the drivespring can then be adjusted so that it arm 16 ahead of the flight-of thearmature. its opposition to the armature movement is virtuallyeliminated before the armature starts. Another important feature is thatthe armature drive spring does not partake of the movement of the pushrod'39,'as it has in all cases heretofore, where the armature has beenstarter from its poles by an inelastic transmission of force andfollowed up by an elastic trans- Heretofore, the spring has moved withthe push rod and thus acquires kinetic energy. The

spring is being moved at a considerable.

speed 'duringits expansive action on the armature. Consequently, thearmature moves through a smaller range and more quietly with less wearand tear on the various moving parts. 'A less'driving force on thearmature suffices because the return spring opposition is practicallyeliminated before the armature starts its flight. 1

The tension of the drive and retu 'n springs, while adfustable and beinga 3 ed so that at certain times it is nearly zero, is never quiterelaxed. Enough tension is provided at times of minimum spring tensionto minimize any noise effect due to lost motion in the connectionsbetween the various moving pa if and when the same exists. For examplsuppose that the bliOCrI 14 does not closely lit the slideway 123 so tat there is a slight space between'the upper edge ofthe block and theadjacent surface of the slideway 'When the parts are positioned as inFig. 1, this lost motion is taken up quietly between the two springsbefore the armature starts to move. It is-thereby taken up before anygreat stress is exerted and consequently a blow of arm 12 on block 1% isavoided; That is, as the push rod-moves to the right, the return springdiminishes in tension and the drive spring will expand progressivelyuntil the upper surface of slideway lo engages the upper edge of block14. The two springs constantly'seek a balance and the result is thatthere is never any considerable force available to take up the lostmotion with a blow. The two parts thus move relat'vely slowly andquietly into contact before theinelastic armature removing force comesinto play. At the end of the downward flight of armature a, the return.spring actsas a cushion or shock absorber to arrest the same. The partsare broughtto rest between springs which seek a balance and the lostmotion is again taken upquietly because of the absence of anyconsiderable driving force to produce a blow.

The. operation of the armature actuating V ditions whichmay beencountered. It also affords an extremely quiet drive with theelimination of violent movement of" the armature and reduction of itsrange of travel. Atthe same time comparatively little power is requiredfor operati0n, -much less infact thanin the magneto shown in my priorPatent No. 1,488,975, above referred to. patent is obtained with theadvantages incident to'the use of the trip in of the armature by aninelastic transmission of force, resulting ingreatly improved operatron.V I

V The invention has been disclosed herein, in an embodiment at presentpreferred, for illustrative purposes but the scope of the invention isdefined by the appended claims rather than by the foregoing description.

What I claim is:

1. In a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, a rocker arm connected to move with thearmature, elastic means acting on the rocker arm and exerting a force onthe armature which is opposed to that of magnetic attraction and whichis less than theforce of magnetic attraction on the rmature whenthe'latter is in contact with its poles, and driving means reciprocablein ya direction at an angle tothat in which the armature moves, saiddriving means operable v onone stroke by an 1nelast1c transmission to-The quiet armature operation. of that llO the rocker arm to overcome theforce of magnetic attraction and move the armature out of contact withits poles and operable on the other stroke to move the rocker arm in theopposite direction and stress said elastic means and cause the armatureto be seated on its poles.

2. In a magneto, of the type wherein an armature moved into and out ofContact with magn c poles, a reel er arm connected to move with thearmature. elatic means acting on the rocker arm and exerting a force onthe armature which is opposed to that of magnetic attraction and whichis less than the force of magnetic attraction on the armature when thelatter is in contactwith its poles, driving means reciprocable in adirection at an angle to that in which the armature moves, said drivingmeans operable on one stroke by an inelastic transmission to the rockerarm to overcome the force of magnetic. attraction and move the armatureout of contact with its poles and operable on the other stroke to movethe rocker arm in the opposite direction and stress said elastic meansand cause the armature to be seated on its poles, and elastic meansthrough which said driving means transmits its force to the rocker armin returning the armature and stressing said first named elastic means.

3. In a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, a rocker arm connected to move with thearmature, said rocker arm on each of two opposite taces provided with aspring seat and the axes of said seats lying in spaced parallel planes,a stationary abutment. a drive spring interposed between the latter andone of said seats, a reciprocable push rod movable alongside said drivespring and having a trip shoulder to engage the rocker arm, and a returnspring carried by the push rod and engaging the other of said seats.

4;. Armature actuating mechanism for a magneto of the type wherein anarmature is moved into and out of contact with magnetic'poles,comprising, a rocker arm for connection to the armature, a reciprocablepush rod having a trio shoulder adapted on one stroke to engage therocker arm, a return spring carried by the push rod and en gaging therocker arm, a stationary abutment, and a drive spring disposed alongsidethe push rod and acting between said abutment and the rocker arm.

5. Armature actuating mechanism for a magneto or" the type wherein anarmature is moved into and out of contact with magnetic poles,comprising, a rocker arm for connection to the armature, drive andreturn springs acting on opposite sides of said rocker arm at laterallyspaced points, and a reciprocable push rod having a trip shoulderadapted on one stroke to engage the rocker arm and initially move it inthe same direction as said drive spring tends to move it.

6. In a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, elastic driving means acting on thearmature in opposition to the torce of magnetic attraction and exertinglPr'J force on the armature when the latter is in contact with its polesthan the force due to magnetic attraction, means operable by aninelastic transmission of force to start the armature away from itspoles, and means or varying the time at which the last named meansstarts the armature and at the same time vary the stress in said elasticdriving means, increasing or diminishing said stress accordingly as thearmature is started later or earlier, respectively.

'7. In a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, elastic driving means acting on thearmature in opposition to the force of magnetic attraction and exertingless force on the armature when the latter is in contact with its polesthan the force due to magnetic attraction. reciprocable driving meansoperable on one stroke by an inelastic transmission of force on thearmature to overcome the force of magnetic attraction and move thearmature out of contact with its poles and operable on the other stroketo move the armature toward its poles and stress said elastic drivingmeans, and means for varying the time at which said reciprocable meansstarts the a mature and at the same time varying the stress of saidelastic driving means.

8. Armature actuating mechanism for a megneto of the type wherein anarmature is moved into and out of contact with magnetic poles,comprising, a rocker arm for connection to the armature, drive and return springs acting in opposite directions on said rocker arm and havingtheir axes in spaced and substantially parallel relation, and areciprocable push rod having a trip shoulder adapted on one stroke toengage the rocker arm and initially move it in the same direction assaid drive spring tends to move it.

Qfrirmature actuating mechanism for a magneto of the type wherein anarmature is moved into and out of contact with magnetic poles,comprising, a rocker arm for connection to the armature, drive andreturn springs acting in opposite directions on said rocker arm andhaving their axes in spaced and substantially parallel relation, areciprocable push rod having a trip shoulder adapted on one stroke toengage the rocker arm and initially move it in the same direction assaid drive spring tends to move it, and means for varying the time atwhich the trip shoulder engages the rocker arm and at the same timevarying the stress of said drive spring. 7 I

10. In a magneto, of the type in which an armatureis moved into and outof contact with magnetic poles, a stationary abutment,

a drive spring acting between said abutment andthe armaturein oppositionto'the forcea drive spring acting between said abutment and thearmaturein opposition to the force of magnetic attraction, a reciprocable memberhavinga trip shoulder to initially move the armature away from its polesby an i11- elastic transmission of force, an abutment onStildll'lQlHbBl', a return spring acting between said last namedabutment and the armature, means for adjusting the position of saidfirst named abutment and at the same time changing the time at whichsaid trip shoulder acts to initially move'the armature, and means foradjusting said abutment independently of the last named means. 7

12. In a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, a rocker arm connected to move with thearmature, a reciprocable push rod having 'a trip shoulder to engage saidarm, an armature return spring carried by the push rod and acting on therocker arm in a direction opposite to that in which said trip shoulderacts, a stationary abutment, and an armature drive spring acting betweensaid abutment and the rocker arm in'opposition to said return spring.

13.1n a magneto, of the type wherein an armature is moved-into and outof contact with magnetic poles, a rocker arm connected to move with thearmature, a reciprocable push rod having a trip shoulder to engage 7said arm,an armature return spring carried by the push rod and acting onthe rocker arm in; direction opposite to that in which said tripshoulder acts, means for varying theposition ofsaid rocker armwith-relation to said trip shoulder, an abutment carried by the lastnamed means, and an'armature drive spring acting between said abutmentand the rocker arm in opposition to said return spring.

1%.11'1 a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, a pivoted rocker arm connected to movewith the armature,a reciprocable push rod having a trip shoulder toengage said arm, an armature return spring carried by the push rod andacting on the rocker arm in a direction opposite to that in which saidtrip shoulder acts, means for moving the pivot of said rocker arm, anaoutment carried by said means, and an armature drive spring actingbetween said abutment and the rocker arm in opposition to said returnsprin v 15. Armature actuating mechanism for a magneto of the typewherein an armature is moved into andout or" contact with magneticpoleacomprising, a rocker arm for connec-' tion to the armature, drive Iand return springs acting in opposite directions on said rocker arm andhaving their axes in spaced and substantially parallel relation, areciprocable push rod having a trip shoulder dapted on one stroke toengage the rocker arm and initially move it in the same direction assaid drive spring tends to move it,-

and means for varying the time at which the trip shoulder engages therocker arm and at the same time varying the stress of said drive spring.increasing or diminishing said stress accordingly as the rocker arm isengaged at later or earlier times respectively. IGJrirmature actuatingmechanism for a magneto of the type wherein an armature is moved intoand out of contact with magnetic poles, comprising, a rocker arm forconnection to the armature, a reciprocable. push rod,

having'a trip shoulder adapted on one stroke to engage the rocker arm, areturn spring carried by the push rod and engaging the rocker arm, alever movable to vary the time at which said trip shoulder engages therocker arnnan abutment connectedto said lever to move therewith, and adrive spring disposed alongside the push rod andacting between saidabutment and the rocker arm.

signature.

PHELPS BROWN.

